Biomaterials, commonly used as implantable orthopedic prosthetic devices are not designed to retain functionality while maintaining compatibility with respect to biological factors at the implant/tissue interface. In order to achieve cytocompatability, it is desirable that the biomaterial surface characteristics at the interface be optimally compatible with pertinent bone cell types. Achieving similar mechanical properties to native tissue insures limited destruction of local cells. The surface texture of the biomaterial is also important to control for orthopedic implant efficacy to closely harmonize the mass and kinetics of the osseous biomolecular events. Previously implantable devices have been fabricated of ceramic, polymer, composite and metallic materials.
Metallic materials which have been used include titanium (Ti), a titanium alloy and a cobalt chromium molybdenum. These metallic materials have been found to have a grain size on the order of microns (μm).
Implant failures have been observed with each of these materials. Investigations have been run for the purpose of finding a technique for eliminating or at least reducing the incidents of bone implant failures in humans. The underperformance of implant has been blamed on incomplete osseointegration (i.e., lack of bonding of an orthopedic implant to a juxtaposed bone), stress shielding and/or the generation of wear debris at articulating surfaces.
Thus, it is desirable to increase the adhesion between the implant and tissue surface (sometimes referred to as osteoblast adhesion) particularly in connection with the metallic surfaces so as to address implant feature issues.